Comparison of Biomechanical Factors Before and After UCL Surgery in Baseball Athletes: A Systematic Review With Meta-analysis

BACKGROUND: Ulnar collateral ligament (UCL) reconstruction (UCLR) and repair (UCLr) are the gold standards in the treatment of UCL injuries. Although return-to-play timelines after UCLR have been established, pitching biomechanical variables are speculated to change after surgical intervention. PURPOSE/HYPOTHESIS: To synthesize the literature and investigate changes in pitching biomechanics in baseball pitchers after UCLR or UCLr. We hypothesized that differences in pitching biomechanics would be observed for both intra- and interpatient comparisons. STUDY DESIGN: Systematic review; Level of evidence, 3. METHODS: We searched 4 electronic databases (PubMed, Web of Science, SCOPUS, and Sports Medicine & Education Index) from inception to February 2020. Data extracted included author and year of publication, study design, sample size, study population, and primary outcome variables. Meta-analysis was performed to produce random pooled effect sizes (▵). RESULTS: We identified 1010 original articles for inclusion. A total of 5 studies were included in the systematic review; of these, 3 studies were included in the meta-analysis. No differences were found in shoulder range of motion (ROM) between post-UCLR and control pitchers (dominant arm external rotation ▵, 0.13°; 95% CI, –0.15° to 4.02°; P = .36); dominant arm internal rotation ▵, –0.20°; 95% CI, –0.74° to 0.35°; P = .48). Mean fastball velocity as well as pitches thrown decreased after UCLR in professional pitchers. Significant differences in elbow extension, elbow extension velocity, and shoulder internal rotation velocity were found among amateur pitchers. CONCLUSION: The results of this systematic review and meta-analysis show that limited differences exist in pitchers before and after UCLR as well as in post-UCLR pitchers and healthy, age-matched controls. UCLR may influence throwing velocity, but it had no effect on either the throwing biomechanics or theROM of baseball pitchers. Although trends appear to be forming, further evidence is needed to understand the effect of UCLR on throwing biomechanics.